Measuring instrument.



Patented 1 Sept. 9, |902.

No. 708,52n.

c. A. Bn'owN- en. emma.

IHEASURING- INSTRUMENT.

(Application led Jan. 80, 1902.)

'(No Model.)

attenuato 'f Tus 'nanars Pirnie co. pHoro-umn., wAsHwnTou. u, c.

UNITED STATES i coLLINs A. BROWN AND ROBERT C. KERR, OF READING, MICHIGAN.

MEAsURlNe INSTRUMENT.

SPECIFICATION formingfpart of Letters Patent N o. 708,520, dated September 9, 1902.

i Application iiled January 30,1902. SerialNo. 91,859. (No model.)

To all whom, t Wray concer-n:

Be it known that we, COLLINS A. BROWN and ROBERT C. KERR, citizens of the United States, residing at Reading, in the county of Hillsdale and State of Michigan, have invented certain new and useful Improvements in Measuring Instruments; and we do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in the adjusting means of calipers, dividers, and other similar measuring instruments.

The object of the invention is to provide improvedadjusting means whereby the instrument may be tirst quickly set to the approximate adjustment and then set to the exact adjustment, the particular object in View being to secure accuracy and sensitiveness in making theffinal and finer adjustment.

With these and other objects in view, which will readily appear as the nature of the invention is better understood, the same consists in certain novel features of construction and combination and arrangement of parts which will be hereinafter fully described, defined in the appended claims, and illustrated in the accompanying drawings, in which- Figure 1 is a side elevation showing the application of the invention to a pair of inside calipers. Fig. 2 is a horizontal section on line 2 2 of Fig. 1 looking in the direction of the arrow. Fig. 3 is a perspective view of the diiterential micrometer-nut. Fig. 4 is a longitudinal section of the same on an enlarged scale.

Referring now more particularly to the drawings, the numerals 1 and 2 represent the legs of a pair of inside calipers, 3 the pivotal connection between the legs, and 4 the bowspring, which spreads the legs in the usual manner.

The legs 1 and 2 are provided with corresponding transverse openings 5 for the passage of the draw-rod 6, which is provided with the opposite threaded portions 7 and 8, one to receive the ordinary nut for coarse adj ustment and the other to receive the differential micrometer-nut for fine adjustment.

l Between these ltwo screw-threaded portions the rod is reduced, as shown at 9, to receive the lower bifurcated end of a plate-spring 10, fixed at its upper end to the leg 1 and to form a shoulder 11. The bifurcated lower end of the spring straddles the reduced portion of the rod and bears against the said shoulder 11 to hold the micrometer-nut in locking engagement with the leg 1, as hereinafter described. Working on the threaded portion 7 of the rod is a nut 12, which bears against a washer 12', interposed between the same and the leg 2, and is employed for coarse adjustment and to set the calipers quickly to the approximate position for measuring. The threaded portion 8 receives the differential micrometer-nut, by which a sensitive adjustment is obtained for setting the calipers to accurate measurement. This micrometer-nut comprises in its construction an outer nut 13, which is provided at one end with lockinglugs 11i to engage seats or notches 15, formed in the outer face of the leg l, by means of which said nut may be held from rotation. This nut is engaged by a hollow threaded stem 16, carried byan inneradju'sting-nut17,the said stem 16 being formed upon its interior with coarse threads 1S to engage the threads 8 on the draw-rod and upon its outer surface with liner threads 19 to engage the threaded surface 2() of the outer nut 13. By this construction when the nut 17 is screwed up the stem 16 advances along the screw-threaded portion 8 faster than it advances along the interior of the nut 13, thus enabling both threaded portions of the draw-rod to be made of the same gage or degree of neness, while at the same time obtaining a finer and more sensitive adjustment through the medium of the nut 17 for sensitively setting the calipers to measurement with the greatest degree of accuracy.

In the use of the invention the nut 12 is first operated to set the calipers quickly to the approximate adjustment. Then the nut 17 is operated to set the calipers to the exact adjustment.

The nut 13 is held against rotation by the engagement of the lugs 14 with the seats or notches 15, and the spring 10 by hearing against the shoulder 11 normally draws the IOO threaded end 8 of the rod inwardly, thereby holding the lugs securely seated in said notches.

The nut 17 is formed With a sleeve 21, which incloses the stem and a portion ot' the nut 13, thereby preventing the entrance of dirt to the threads. The outer surfaces of this sleeve and the nut 13 may be graduated to enable the degree of adjustment of the nut 17 to be readily determined.

From the foregoing description, taken in connection with the accompanying drawings, it is thought that the construction, mode of operation, and advantages of our improved adjusting means for calipers Will be readily apparent Without requiring an extended explanation.

Various changes in the form, proportion, and the minor details of construction may be resorted to Without departing from the principle or sacrificing any of the advantages of this invention.

Having thus described the invention, what We claim as new, and desire to secure by Letters Patent, is-

1. In adjusting mechanism for calipers and like measuring instruments, the combination with the legs of the instrument provided with openings; of a draw-rod passing therethrough and provided with opposite threaded portions, an adjustingnut Working on one of said threaded portionsforsettingthecalipers tothe approximate adjustment, and a differential micrometer-nut upon the other threaded portion of the rod for setting the calipers to exact adjustment, the said differential nut comprising an outer nut, an inner nut having an exteriorly-threaded portion to engage said outer nut, and an interiorly-threaded portion to engage the threads on the draw-rod, and

means for holding the outer nut against rotation, substantially as described.

2. In adjusting means for calipers and like measuringinstruments, the combination with the legs of the instrument provided With open ings; of a draw-rod extending through said openings and provided with opposite threaded portions, a nut engaging one of the threaded portions for setting the calipers to approximate adjustment, anda differential micrometer-nut engaging the other threaded portion of the rod for setting the instrument to the exact adjustment, the said micrometer-nut comprising an outer nut provided with lugs to engage seats in the adjacent leg of the instru ment and formed with interior screwthreads, and an inner nut having a stem formed With interior screw-threads to engage the rod and With exterior finer threads to engage the threaded surface of the outer nut and having a sleeve inclosing said stem and outer nut, substantially as described.

3. In adjusting means for calipers and other like .measuring instruments, the combination With the legs of the instrument; of a drawrod passing therethrough, said rod being provided with opposite threaded portions, a nut Working upon one of the threaded portions of the rod for setting the instrument to the approximate adjustment, a diterential micrometer-nut Working upon the other threaded portion of the rod for setting the instrument to the exact adjustment, one of the members of said micrometer-nut being provided With lugs for engaging the adjacent leg ofthe instrument for holding it against rotation, and means engaging the rod for normally drawing the same in one direction for maintaining said lugs in engagement, substantially as and for the purpose set forth.

4. In adjusting means for calipers and other like measuring instruments, the combination With the legs of the instrument; of a drawrod extending therethrough, said rod being provided with opposite threaded portions and an intermediate shoulder, a nut Working upon one of the threaded portions of the rod for setting the instrument to the approximate adjustment, a differential micrometernut working upon the other threaded portion of the rod for setting the instrument to exact adjustment, one of the members of said micrometer-nut being provided with lugs to engage notches in the adjacent leg of the instrument to lock it against rotation, and a platespring secured to said leg and bearing against said shoulder to draw the rod in one direction to hold said lugs in locking engagement, substantially as described.

In testimony whereof We have hereunto set our hands in presence of two subscribing Witnesses.

COLLINS A. BROWN. ROBERT C. KERR.

Witnesses:

CHAs. W. STONE, DALMER C. GRovER.

ICO 

